1. Field of the Invention
This invention relates, generally, to devices that insert biopsy markers at biopsy sites.
More particularly, it relates to a device that employs a spring to eject a marker into tissue from a side port of the device.
2. Description of the Prior Art
Devices that eject biopsy markers from a side exit port are well-known. An example of such a device is disclosed in U.S. Pat. No. 7,625,397 and an earlier example is disclosed in U.S. Pat. No. 6,220,248.
The primary drawback of the earlier devices is that said devices provide no means for controlling the amount of force used to eject the marker. Thus, the power applied to the marker to eject it is determined by the amount of force applied by the physician and such force may vary for each procedure, even for the same physician. Thus, some markers are ejected with greater force than others and thus the placement of the marker relative to the desired position will vary.
Thus there is a need for a device that ejects the marker with the same amount of force each time it is used. Such a device would operate independently of any force applied by a user and would ensure a uniform, repeatable placement of the marker.
However, in view of the art considered as a whole at the time of making the present invention, how to provide the needed apparatus was not obvious to those of ordinary skill in the art.